This invention relates to an apparatus for controlling an elevator at the occurrence of an earthquake, which operates the elevator safely when an earthquake occurs.
A prior-art apparatus for operating an elevator at the occurrence of an earthquake is disclosed in Japanese patent application publication No. 42155/1973, in which when an earthquake sensor had been activated, a cage is quickly stopped at the nearest floor at which it can stop, irrespective of the scale of the earthquake wih the highest priority given to safety, whereby the elevator is stopped and rendered unserviceable. Further, there has recently been adopted a passive safety measure wherein, as stated in the "Manual of Technical Standards of Elevators" (issued by the Japan Elevator Association), 1984 issue, p. 256, a plurality of earthquake sensors are installed, the scale of an earthquake is decided after the lapse of a predetermined time limit as determined by the combined output states of the plurality of earthquake sensors (a time limit at which the earthquake is predicted to have ended), and depending on the scale only an elevator is automatically reset to resume normal operation at the time of a small-scale earthquake, whereas the elevator is taken out of services without regard to the presence or absence of any damage at the time of a large-scale earthquake.
More specifically, the safety system has a low-level earthquake sensor which operates upon sensing a low-level earthquake, and a medium-level earthquake sensor which operates upon sensing a medium-level earthquake. When either of the sensors operates, a cage is forcibly stopped at the nearest floor possible, and the elevator is rendered unserviceable. Thereafter, the scale of the earthquake is determined upon the lapse of a period of time in which the earthquake is anticipated to end. When the level of the earthquake is low, it is presumed that there is no damage to the elevator system, and the elevator is automatically reset to the normal state of operation and rendered serviceable after the lapse of the predetermined period of time. On the other hand, when the level of the earthquake is medium or above, it is presumed that there is damage to the elevator system and that the elevator should be taken out of service and whether or not any damage to any of the elevator's parts is checked by performing an inspection operation. After the completion of the inspection operation, in the absence of any abnormality, the elevator is reset to resume normal operation, whereas in the presence of any abnormality, the elevator is held out of service until the malfunctioned part is repaired.
As stated above, the apparatus for operating the elevator at the occurrence of an earthquake has been constructed relying entirely on the decision based on the presumption.
Since the prior-art apparatuses for controlling an elevator at the occurrence of an earthquake are constructed as described above, an operating system with safety taken into consideration when viewed from the users' side of the elevator is provided. However, since small earthquakes happen frequently, the elevator becomes unusable temporarily or for a predetermined time on each occasion. This had led to the problem that, for the sake of safety, the performance of the elevator, which is an important means of transportation in the vertical direction of buildings is sometimes lowered, resulting in sluggish elevator service in the building.
Further, even in a range exceeding the small earthquakes, all earthquakes do not inflict damages to the elevator system. In this regard, there has been the problem that the elevator becomes unusable at the occurrence of such an earthquake.